The disclosure described herein was developed by employees of the United States Government and may be manufactured and used by or for the United States Government for governmental purposes without the payment of any royalties thereon or therefore.
This disclosure relates generally to the field of telescope mirrors.
Telescopes in space use large mirrors to capture images; the surface figure of a telescope mirror must precisely conform to specified dimensions in order to capture images clearly. Therefore, distortion in a telescope mirror needs to be minimized. Fabrication and testing of such a mirror on earth may be complicated by the presence of distortion in the mirror due the mirror's own weight at 1 g; this self-weight distortion is not present in space in the absence of gravity (i.e., at 0 g). The mounts that hold the mirror in place in the telescope may also induce stress and distortion in the mirror; any distortion induced by the mirror mounts will be present both on earth and in space. Mounting methods that theoretically produce little or no mirror distortion exist, but such methods may be irreversible if distortion is seen in the mirror after mounting, and may employ interfaces that are not compatible with extreme space environments.
To increase telescope resolution, the telescope's primary aperture may be increased by increasing the mirror size. The mirror size is limited by the total mass that may be successfully launched into space, particularly for missions having a high-energy orbit. Lightweighting the mirror material allows for launching of a correspondingly larger mirror into space; however, as the mirror material is made more lightweight, the stiffness of the mirror material decreases, resulting in greater distortion in the mirror from gravity and from the mirror mounting. Reduced mirror stiffness increases the cost and risk associated with the fabrication, validation, integration, and verification of a lightweight mirror with a high-precision on-orbit surface figure.